Receiver Data Alignment Using Discontinuity Detection
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Solution Overview
Problem
Conventional data alignment methods in communication systems, such as Fibre Channel, are inefficient due to the need for alignment markers, which increase overhead and reduce transmission bandwidth, and require significant time to achieve alignment, especially in high-speed links like 32GFC, where the mean alignment delay can be as high as 0.5 milliseconds.
Innovation Solution
The implementation of a receiver system that uses a tapped delay line and exclusive disjunction combinatorial circuits to generate a discontinuity-detection signal by canceling out repeated sequences, allowing for rapid alignment without alignment markers, by correlating the input data with a training pattern and detecting codeword boundaries within approximately two codeword durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alignment markers are added to indicate message boundaries, then data alignment can be achieved, but transmission bandwidth is reduced due to overhead
Solution Approach 1:
The invention extracts and removes the alignment marker overhead from the transmission stream. Instead of adding dedicated alignment markers, the system uses the existing training pattern structure and polynomial function properties to derive alignment information, thereby eliminating the bandwidth overhead while maintaining alignment accuracy
Solution Approach 2:
The invention introduces an intermediary approach by using the polynomial function relationship between repeated sequences as a mediator. The discontinuity detection mechanism acts as an intermediary that translates the polynomial pattern relationships into alignment signals without requiring additional transmission resources
2Measurement precision
If conventional correlator-bank implementations are used for data alignment, then alignment can be achieved, but logic resource consumption increases significantly
Solution Approach 1:
The invention segments the alignment problem into two independent stages: discontinuity detection (identifying potential alignment points) and verification (confirming alignment). This segmentation allows each stage to use simplified logic rather than requiring a full correlator bank, reducing overall device complexity while maintaining accuracy
Solution Approach 2:
The invention performs partial correlation action by first detecting discontinuities that indicate potential alignment points, then verifying only at those specific points. This partial action approach avoids the excessive computation of a full correlator bank that would check all possible positions, reducing logic resources while maintaining alignment accuracy
3Measurement precision
If alignment markers are used in high-speed links like 32GFC, then data alignment can be achieved, but alignment delay increases to approximately 0.5 milliseconds
Solution Approach 1:
The invention performs preliminary action by detecting discontinuities in the training pattern that pre-indicate codeword boundary positions. This preliminary detection allows the system to prepare for alignment before actual data transmission begins, significantly reducing the alignment delay that would otherwise occur during active data processing
Solution Approach 2:
The invention skips the time-consuming process of checking all possible alignment positions by using discontinuity detection to directly identify likely boundary positions. This rushing through approach allows the system to jump to probable alignment points without exhaustive search, reducing alignment delay from 0.5 milliseconds to a fraction of that time
Data Source
AI summary
An apparatus and method therefor for a receiver are disclosed. In this apparatus, at least one delay line is configured to receive input data from a communication lane and provide repetitions of the input data delayed with respect to one another. An exclusive disjunction combinatorial circuit is configured to receive the input data and the repetitions thereof and to generate a discontinuity-detection signal for codeword alignment responsive to successive linear combination by exclusive disjunction of the input data and the repetitions thereof to cancel out portions of repeated sequences of the input data for detection of at least one type of discontinuity in the input data.